Bad Ring Gear?

This ring gear is about 6 years old. The one I took out looked almost as bad.
Starter is 5 years old.
Bendix is clean and dry.
Now I'm wondering what's going on.
Damage area is about 6" long, doesn't go all the way around.

I can remember 2 times when I didn't the idle up high enough when starting and the bendix didn't disengage, but don't think it would have done this.


 

The damage is always going to be limited to usually one or two areas of the gear because engines have places in the revolution where they are most likely to stop. I think that I would be looking for something limiting the travel of the drive, keeping it from engaging as far as it should.
 
On a four cylinder engine. The wear will be in two
places. I think I would replace the drive also.

The drive should kickout as soon as the engines
fires.
 
Two questions on my mind? Is the ring gear on far enough? Are the teeth hardened like they should be?

Gear hardening is a real art. The teeth need to be hard enough on the surface to take the shock and wear, yet soft enough in the core that the teeth don't crack off. This takes the proper steel to begin with, then a proper furnace with proper carbon atmosphere, held for a sufficient time and temperature, then quenched to harden followed by tempering to toughen them and reduce brittleness. It adds to the cost quite a bit.
 
(quoted from post at 18:38:42 10/17/14) Two questions on my mind? Is the ring gear on far enough? Are the teeth hardened like they should be?

Gear hardening is a real art. The teeth need to be hard enough on the surface to take the shock and wear, yet soft enough in the core that the teeth don't crack off. This takes the proper steel to begin with, then a proper furnace with proper carbon atmosphere, held for a sufficient time and temperature, then quenched to harden followed by tempering to toughen them and reduce brittleness. It adds to the cost quite a bit.

How would the factory make most the correct hardness and one or two soft? That would be quite a trick!
 
Engines usually stop in about the same position each time. It is normal for starter ring gears to wear in one or two areas.

Dean
 
Agreed, cdmn.

I expect that the Chinese manufacturers from which aftermarket ring gears are sourced have not mastered this art.

Dean
 
The teeth on a ring gear are not hardened.
You can easily remove burrs, etc on one with a file.
If they were hardened they would get annealed when you heat them to put them on.
The bendix gear is fairly hard however.
I don't know why he's eating gears either.
I doubt it is caused by 12V. 12V can cause the bendix to shatter on occasion and maybe wear the RG badly in a couple of areas but not THAT bad.
I would make sure the bendix is correct for that application.
It is odd for sure.
 
(quoted from post at 21:38:42 10/17/14) Two questions on my mind? Is the ring gear on far enough? Are the teeth hardened like they should be?

Gear hardening is a real art. The teeth need to be hard enough on the surface to take the shock and wear, yet soft enough in the core that the teeth don't crack off. This takes the proper steel to begin with, then a proper furnace with proper carbon atmosphere, held for a sufficient time and temperature, then quenched to harden followed by tempering to toughen them and reduce brittleness. It adds to the cost quite a bit.
The ring was properly seated.
One thing does come to mind. I was not around when a neighbor put it on for me, and it's possible that he over heated it and drew the temper out. I put the tractor back together and never gave that a thought at the time. That's when I installed a new starter and bendix. A couple of years later as some have said the teeth on the bendix let go. It locked the flywheel up until I did a split of about 1/4" at which point the broken tooth fell out. I then replaced the "new" bendix with the old one.
It's a 12 volt conversion done years before I bought the tractor.
I'm aware of the fact that the motor will stop at 4 different places, why it chooses this place about 1/2 of the time is a mystery of science.
I thought maybe the ring may have spun on the flywheel, but didn't see any evidence of that. Out of curiosity I'm going to do a file and spark test on it today to try and check hardness. For grins I'm also going to try hardening a couple of teeth to see if it will harden.
I'll check the starter for runout today. I may also take it to a rebuild shop and see what they think.
My plan on installing the new ring is to pull the flywheel out of the freezer and barely heat the ring enough to let it fall on. I'd love to go old school and heat in oil, but I don't have anything large enough to hold it. Next best thing is to oven heat it, just need to find out how hot to set the oven.
 
If the pictured ring gear is a Chinese made aftermarket unit, I suspect that it is made of poor steel. If so, such damage in 5 years is not surprising, given the 12V conversion.

Put the flywheel in the freezer for a couple of hours and oven heat the ring gear to the maximum temperature of your oven, which is probably no more than 500 F. It should go together easily if you do so without delay.

I would probably tack weld it in 3 or 4 places.

Dean
 
(quoted from post at 08:48:59 10/18/14) If the pictured ring gear is a Chinese made aftermarket unit, I suspect that it is made of poor steel. If so, such damage in 5 years is not surprising, given the 12V conversion.

Put the flywheel in the freezer for a couple of hours and oven heat the ring gear to the maximum temperature of your oven, which is probably no more than 500 F. It should go together easily if you do so without delay.

I would probably tack weld it in 3 or 4 places.

Dean
Probably came from India.
File checked the old and new with a file (don't have a way to check Rockwell) and they were both surprisingly soft. For grins I tried to oil, then water harden, no change, not enough carbon.
May add a couple of MIG tacks just because when I go back together.
Putting the flywheel in the freezer today, should be cold enough when I get back up here in two weeks.
Zero runout on the starter, washed the bendix, it was clean.
Anyone else have this type problem?
 
[b:654c4848f0]I'm aware of the fact that the motor will stop at 4 different places, why it chooses this place about 1/2 of the time is a mystery of science.[/b:654c4848f0]

This is a 4 cylinder so the engine will only stop in 2 places.
So stopping in this spot 1/2 of the time works out in the law of averages.
 


I too, would scratch head here, considering the comparative
start cycles Vs. the family sedan.........

Since both starter and ring gear were replaced about the same
time, I would question whether the teeth on the ring gear
and / or the bendix are matched to each other.

It'll take some investigation as the number of teeth for both
ring and starter, .... I'll leave that to you.

While you have them both off, however, compare the bendix
in mesh with the ring gear (on fairly good teeth) and check for a
decent match.
Turning the bendix will give you a good idea as to whether or not
the teeth mesh well, or if mismatched, tend to 'wipe' (grind)
against the next tooth in succession..........

.
 
I also should have mentioned induction hardening and flame hardening as common-place hardening processes.
 
Besides outright fraud, the process could have been induction hardening, which involves placing the gear inside a concentric copper ring, turning on the high-frequency power, rotating the part, turning off the power, dropping the part into a quench, and then tempering soon after. Depending upon the automation, or the attention of a manual operator, some could go through without being heated.
It could be a bad batch of steel. Without the expense of sampling and testing, you wouldn't notice. The "lean manufacturing" idea is to trust process control and certifications and not do quality control by final inspection.
I would guess that the bottom feeders who take these small aftermarket contracts are slow adopters of these quality ideas.
If it comes down to liability, the marketing company would be separate from the manufacturing company, with small assets so that it could go bankrupt without suffering much loss from lawsuits. Anyway, how likely will anyone be hurt by a worn-out starter ring gear/

A particularly notorious case involved counterfeit screws from the mid-1980's. (Search for Quality Digest + Stump).
As far as I know, no corporate Vice President in charge of taking a hit for the team, ever got prosecuted.
 
May have found the culprit. This is the bendix that was on the tractor when I bought it. The replacement I bought along with the new starter shucked some teeth, so I put this one in.
Second pic shows that it's only been engaging half way on the ring.
Don't know if the front of the teeth are supposed to be chamfered or not. Tried looking at the old rusted ring from years gone by and it looks like it had full tooth depth engagement.
New one on order from this site.
Hope this cures my ills.

 
(quoted from post at 16:10:25 10/17/14)
The damage is always going to be limited to usually one or two areas of the gear because engines have places in the revolution where they are most likely to stop. I think that I would be looking for something limiting the travel of the drive, keeping it from engaging as far as it should.

YUP
 

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